2 added 4 characters in body edited Mar 9 '17 at 7:39 Martin - マーチン♦ 34.7k99 gold badges117117 silver badges245245 bronze badges The answer is basically correct (see note at the end of my answer about significant figures) but there is a simpler method, using a dilution factor. The original volume of your solution was 2 mL, and the final volume was 12 mL, so the dilution factor is simply $$\frac{2}{12}$$. The original concentration times the dilution factor gives the final concentration: $$\mathrm{10\frac{mg}{L}~*\frac{2}{12} = 1.7\frac{mg}{L}}$$$$\pu{10\frac{mg}{L}}\cdot\frac{2}{12} = \pu{1.7\frac{mg}{L}}$$ Note that only 2 significant figures were given in the problem and your answer reported 3. The answer is basically correct (see note at the end of my answer about significant figures) but there is a simpler method, using a dilution factor. The original volume of your solution was 2 mL, and the final volume was 12 mL, so the dilution factor is simply $$\frac{2}{12}$$. The original concentration times the dilution factor gives the final concentration: $$\mathrm{10\frac{mg}{L}~*\frac{2}{12} = 1.7\frac{mg}{L}}$$ Note that only 2 significant figures were given in the problem and your answer reported 3. The answer is basically correct (see note at the end of my answer about significant figures) but there is a simpler method, using a dilution factor. The original volume of your solution was 2 mL, and the final volume was 12 mL, so the dilution factor is simply $$\frac{2}{12}$$. The original concentration times the dilution factor gives the final concentration: $$\pu{10\frac{mg}{L}}\cdot\frac{2}{12} = \pu{1.7\frac{mg}{L}}$$ Note that only 2 significant figures were given in the problem and your answer reported 3. 1 answered Mar 9 '17 at 6:15 airhuff 15k77 gold badges3232 silver badges158158 bronze badges The answer is basically correct (see note at the end of my answer about significant figures) but there is a simpler method, using a dilution factor. The original volume of your solution was 2 mL, and the final volume was 12 mL, so the dilution factor is simply $$\frac{2}{12}$$. The original concentration times the dilution factor gives the final concentration: $$\mathrm{10\frac{mg}{L}~*\frac{2}{12} = 1.7\frac{mg}{L}}$$ Note that only 2 significant figures were given in the problem and your answer reported 3.